The preferred embodiment concerns a printer or copier in which transverse folds formed in an endless carrier material are aligned on a position marking. The preferred embodiment also concerns a method for controlling such a printer or copier as well as a sensor arrangement for determination of the position of the transverse fold relative to an adjacent margin hole of an endless carrier material provided with margin holes.
In known high-capacity printers, in particular in electrophotographic high-capacity printers with a printing capacity of ≧50 sheets DIN A 4 per minute, an exact positioning of the print image on the carrier material to be printed is important in order to enable a simple further processing of the printed carrier material and a high print quality of printer products produced with this printed carrier material. Given printing of endless carrier material with transverse folds provided in the carrier material, in particular the position of the print image relative to the transverse fold is thereby decisive. Upon insertion of the endless carrier material into the printer, a transverse fold is thereby directed towards a position marking. Due to this alignment and parameters of the carrier material preset in the printer, which parameters in particular comprise the interval between two transverse folds, the positions of further transverse folds in the printer or copier are known to a control unit of the printer.
A portion of the typically-used endless carrier materials is provided with margin holes that are arranged at a fixed spacing relative to one another. Another portion of the carrier materials typically used comprises printed markings. Both the margin holes and the printed markings can be detected by the printer or copier with suitable sensor arrangements. The bearing of the endless carrier material in the printer or copier can be continuously monitored and checked with the aid of the detected positions. The positions of further transverse folds present in the carrier material relative to the margin holes or to the printed markings are also known via the preset parameters of the carrier material.
Given carrier material with margin holes, a margin hole tolerance of ±2 mm at 2 m is typical, whereby given a typical spacing of 1 m between a hole sensor and fold marking a fold deviation of ±1 mm results. It is also assumed that a setting precision of ±1 mm is present given alignment of the transverse fold on the fold marking. Because the printer or copier is also kept in operation, a further deviation of ±1 mm is assumed that in particular is dependent on the bearing of the carrier material in the printer, the tension of the carrier material upon transport in the printer or copier, the thickness of the carrier material, the surface of the carrier material as well as on the positioning of the hole sensor. A possible total deviation of the real margin hole position by ±3 mm thereby results relative to the desired margin hole position at a hole detection sensor arranged, for example, after a rotating frame.
In particular given a spacing of the transverse folds of 11 and 4/6 inches and a hole interval of ½ an inch, the three successive folds have different bearings relative to the adjacent margin holes. Given alignment of a fold marking and association of a hole spaced with a fixed hole count, an incorrect evaluation of the bearing of the transverse fold relative to the adjacent hole can occur as a consequence of these possible deviations of ±3 mm, whereby the transverse fold can also be associated with a different margin hole than the adjacent one, which different margin hole is not a margin hole adjacent to the transverse fold. The spacing between two folds is also designated as a form length. The described problems occur given all form lengths of N and ⅙ inches, N and 2/6 inches, N and 4/6 inches and N and ⅚ inches, whereby N is a whole-number value.